Currently, multiple Controller Area Network (CAN) interfaces are applied to only a few fields mainly for the purpose of connecting with CAN buses having different CAN protocol formats or different CAN communication rates as desired. A Digital Signal Processor (DSP) chip providing multiple CAN interfaces on most Micro Controller Units (MCUs) supports only up to 2 CAN interfaces and hence has limited extensibility. A CAN communication chip with extensibility is generally controlled by a Serial Peripheral Interface (SPI) bus. A DSP chip providing multiple SPI interfaces on most MCUs supports only up to 2 SPI buses, and each of the SPI interfaces generally corresponds to only one CAN communication chip.
Nowadays, the multiple-CAN interface technologies generally utilize the above two manners, both of which have a limitation of being incapable of supporting an application having more than two CAN communication interfaces. The manner using a CAN controller on the MCU has the highest processing efficiency, but cannot support more CAN interfaces due to a hardware limitation, while the manner of extending the CAN interfaces through the SPI is limited by the number of the SPI buses.